Hi been lurking round here for a while and found a lot of help for various issues over the years without having to post. But I can't seem to find a solution for this one. I have a 2009 iMac running OX 10.8.5 over the last few weeks it keeps ejecting one of my 3 external hard drives. A WD 3 TB drive. I have had it for over 5 years and it worked perfectly until a few weeks ago. My iMac suddenly started ejecting the drive and showing the message that the drive had not been ejected properly just after it booted up each day. I restarted the machine and the same thing happened. I unplugged the drive and re plugged it in, it recognised the drive showing the drive on finder and the desktop, then it promptly ejected it and the ejection message popped up again. I shut down swapped USB ports restarted but the same thing happened again. I bought a new USB cable, thinking that may be the issue, and the same thing happened. I tried running disc utility on it but it ejected before I could run it. So I took the HD to a local computer shop to get it checked. The drive the cable and power supply have been checked and everything is fine and the drive is in perfect condition with no errors. After I had it checked I plugged it back in. Drive showed up on the desktop, and I opened finder clicked on the drive and waited. The machine ejected it about 30 seconds later. SMC reset did not work. PRAM reset did not work. Restart did not work. It is not the drive running time machine (i noticed others have the same issue with a time machine backup drive) I have a LaCie drive for that. Can anyone offer any ideas how to get my machine to recognise the drive again. Many thanks for any suggestions.